Synthesis, spectral characterisation, and electrochemistry of bis-(2,2′-bipyridine)(1-alkyl-2-(naphthylazo)imidazole)ruthenium(II) complexes: X-ray crystal structure of [bis-(2,2′-bipyridine)-{1-ethyl-2-(naphthyl-α-azo)imidazole}ruthenium(II) perchlorate

Heteroleptic tris-chelates, [Ru(bpy)2(α/β-NaiR)](ClO4)2 (bpy = 2,2′-bipyridine; α/β-NaiR = 1-alkyl-2-(naphthyl-α-azo)imidazole, α-NaiR and 1-alkyl-2-(naphthyl-β-azo)imidazole, β-NaiR) have been synthesized either by reacting Ru(bpy)2Cl2 and α/β-NaiR in presence of 2 equivalent of AgNO3 or from Ru(bpy)2Cl2 + [Ag(α/β-NaiR)2](ClO4) reaction under refluxing condition in MeCN. The single crystal X-ray diffraction study in one case, and by other spectroscopic studies has supported the structure of the complexes. All the complexes show metal-to-ligand charge transfer (MLCT) transitions in the visible region. Cyclic voltammetric studies exhibit high potential Ru(III)/Ru(II) (1.2–1.3 V vs. SCE) and three successive ligand reductions at negative to SCE in acetonitrile solution.

Graphical abstractTitle compounds have been synthesized by Ag-assisted route to remove Cl from Ru(bpy)2Cl2 followed by chelation with NaiR (1-alkyl-2-(naphthyl-α/β-azo) imidazole). The structure has been established by X-ray crystallography. Redox property gives Ru(III)/Ru(II) couple and ligand reductions.Figure optionsDownload full-size imageDownload as PowerPoint slide